Why Film "Tears on the Line": Typical Mistakes in Polyethylene Processing
3 Feb 2026
Polyethylene film breaks on the production line are one of the most common problems in extrusion and polymer processing. Lost time, excess raw material consumption, reduced productivity and unstable quality of the finished product are all direct consequences of errors in processing technology.
In this article we will examine why film tears on the line, which factors affect its strength and how to eliminate the typical causes of defects.
Main causes of polyethylene film breaks
1. Incorrectly chosen raw material
One of the key causes is a mismatch between the polyethylene grade and the requirements of the specific product.
Problems most often arise because of:
- unsuitable polyethylene density;
- unstable molecular weight distribution (MWD);
- using grades whose actual properties differ from the datasheet values;
- an incorrect combination of several grades in the formulation.
Linear polyethylenes are particularly sensitive to these factors, where even small deviations in MWD can lead to loss of strength and instability of the weld seam.
2. Formulation errors
Even quality raw material does not guarantee a stable result with an incorrect formulation.
Typical errors:
- excessive simplification of the formulation;
- incorrect introduction of recycled material;
- absence of stabilizers;
- ignoring the compatibility of components.
When changing the formulation, you must take into account that each component "reveals" its properties within a certain temperature range. In multicomponent blends this is especially critical.
3. Incorrect temperature settings
Violating temperature settings is one of the most frequent reasons the film tears right on the line.
Main problems:
- melt overheating, leading to polymer degradation;
- insufficient heating, impairing the fusion of components;
- an uneven temperature profile across the extruder zones.
Even with ideal thickness uniformity, the film can lose strength if the structure of the material has been formed incorrectly.
4. Problems with film thickness uniformity
Thickness uniformity directly affects mechanical strength. Thin areas of the web become "weak spots" where the breaks occur.
Causes of thickness variation:
- incorrect die head adjustment;
- contamination of the die orifices;
- unstable melt pressure;
- equipment wear.
Thickness control and timely maintenance of the equipment are a mandatory condition for stable line operation.
5. Incorrect cooling and crystallization
After forming, the film must pass through a correct cooling stage. Cooling that is too fast or uneven leads to:
- internal stresses;
- brittleness of the material;
- reduced tear resistance.
Properly organized cooling ensures the formation of a stable crystalline structure of the polyethylene.
6. Using recycled material without adapting the technology
Recycled raw material can either worsen or improve film properties — it all depends on the approach.
Errors when working with regranulates:
- no sorting;
- unstable composition;
- an incorrect percentage of addition;
- no adjustment of processing conditions.
With competent selection, recycled material (for example, recycled shrink film or PE sacks) can have a positive effect on the physical and mechanical properties of the film.
How to prevent film breaks on the line
To ensure stable production, it is recommended to:
- carefully select raw material for specific tasks;
- test and adjust formulations;
- adapt temperature settings to the MWD of the components;
- control the thickness uniformity of the web;
- take the influence of recycled material into account;
- service the equipment regularly.
An integrated approach makes it possible not only to eliminate breaks but also to increase the overall efficiency of polyethylene processing.
Conclusion
Polyethylene film breaks are not a "normal occurrence" but a signal of technological errors. In most cases the problem is solved by adjusting the formulation, the processing conditions or the equipment setup.
Understanding the relationship between raw material, technology and performance characteristics makes it possible to obtain a stable product with predictable properties.
